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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 242 · 40 questions
TalentJR

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

NameDateTime takenScore ___ / 40
  1. 1.749 − 549 =
  2. 2.751 − 451 =
  3. 3.286 + 245 =
  4. 4.644 + 641 =
  5. 5.928 − 159 =
  6. 6.225 + 443 =
  7. 7.480 + 421 =
  8. 8.903 − 145 =
  9. 9.637 + 636 =
  10. 10.523 − 136 =
  11. 11.562 − 181 =
  12. 12.170 + 311 =
  13. 13.440 + 445 =
  14. 14.149 + 568 =
  15. 15.837 − 301 =
  16. 16.493 − 321 =
  17. 17.622 − 483 =
  18. 18.513 − 155 =
  19. 19.162 + 332 =
  20. 20.564 − 222 =
  21. 21.782 + 391 =
  22. 22.762 + 439 =
  23. 23.162 + 677 =
  24. 24.556 − 148 =
  25. 25.870 − 321 =
  26. 26.439 + 242 =
  27. 27.636 + 199 =
  28. 28.522 + 376 =
  29. 29.500 − 141 =
  30. 30.146 + 185 =
  31. 31.760 − 431 =
  32. 32.874 − 339 =
  33. 33.971 − 246 =
  34. 34.706 + 481 =
  35. 35.183 + 491 =
  36. 36.357 + 614 =
  37. 37.624 − 267 =
  38. 38.278 + 175 =
  39. 39.592 − 286 =
  40. 40.341 + 135 =

Answer key

  1. 200
  2. 300
  3. 531
  4. 1285
  5. 769
  6. 668
  7. 901
  8. 758
  9. 1273
  10. 387
  11. 381
  12. 481
  13. 885
  14. 717
  15. 536
  16. 172
  17. 139
  18. 358
  19. 494
  20. 342
  21. 1173
  22. 1201
  23. 839
  24. 408
  25. 549
  26. 681
  27. 835
  28. 898
  29. 359
  30. 331
  31. 329
  32. 535
  33. 725
  34. 1187
  35. 674
  36. 971
  37. 357
  38. 453
  39. 306
  40. 476

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